This invention relates to a method of mineral concentrate redress for upgrading a concentrate to smeltable ore.
Concentrates generated in any process, which is typically but not essentially a gravity process, frequently require to be upgraded preferably to a smeltable grade ore. Where the desired component in the primary concentrate has a higher specific gravity than the accompanying gangue, then the application of a redress technique utilizing gravity may be used to separate the desired component from the gangue and thus concentrate the desired constituent.
Several methods and devices exist to enable the separation to be effected, but these are not automated and do not deal with the associated functions involved.
Many designs and arrangements of re-concentrator table are available and have been widely used, for example the Gemini table, which is adjusted to vary the ratio of concentrate to middlings and tailings by varying the water supply to the table and by varying a bumper stop adjustment which controls the amount of vibration.
It is one object of the present invention to provide a method for controlling the supply of material to a re-concentrator table to improve efficiency of operation.
According to a first aspect of the invention there is provided a method of concentrating a slurry of particulate ore material for separation of a smeltable concentrate comprising:
providing a re-concentrator table arranged to separate concentrate ore at a concentrate discharge from middlings and tailings;
setting the re-concentrator table such that the concentrate forms a smeltable concentrate and thus at least the middlings contain significant quantities of the concentrate to be collected;
feeding the ore material to the table from a feeder;
operating the table for a first period of time during which both the middlings and tailings are returned to the feeder for recirculation to the table;
after the first period, for a second period, continuing to operate the table while directing at least the tailings to discard;
and collecting the concentrate ore.
Preferably during the second period the middlings continue to return to the feeder.
Preferably the operation of the table is halted after the second period for a dwell period.
Preferably the operation of the table is halted at a time when material remains in the feeder ready for receiving a further batch.
Preferably the first period of time constitutes the majority of the operating time so that the feed materials are re-circulated over the table a number of times during the first period.
Preferably the second period is sufficient to reduce the quantity of material in the feed from an original batch down to a required reduced amount for maintaining in the feeder ready to receive a subsequent batch.
Preferably the feeder is arranged to receive a batch from a batch machine supplying the feeder.
Preferably the table includes a water supply and wherein the feeder includes a water overflow such that the water returned to the feeder with the middlings and tailings is discharged from the feeder.
Preferably the feeder comprises a hopper for receiving a batch of material and a feed screw for carrying the particulate ore from the hopper upwardly from the hopper leaving water in the hopper for discharge onto the table.
Preferably there is provided a screening system optionally including a magnetic separator between the feeder and the table.
Preferably there is provided a diverter valve controlled by a timer for diverting the tailings from the return during the first period to the discard during the second period.
Preferably the table, the hopper, the feed screw, the diverter valve and the tailings pump are mounted on a frame as a common construction.